How to Manage Pests

UC Pest Management Guidelines

Adult omnivorous leafroller.

Pomegranate

Omnivorous Leafroller

Scientific name: Platynota stultana

(Reviewed 10/13, updated 10/13)

In this Guideline:


Description of the pest

Omnivorous leafroller can be a significant pest. The larvae are cream colored with black or brown head capsules and resemble other leafrollers, except that they have white tubercles at the base of each bristle along the top of the abdomen. Omnivorous leafrollers are more common in interior valleys and southern California mountain orchards, especially those next to vineyards, than in orchards in coastal areas or at higher elevations of the Sierra Foothills. Orchards may be invaded by omnivorous leafroller moths that develop on host plants outside the orchard. Infestations are often spotty, making monitoring difficult. They have three to four generations per year.

The adult omnivorous leafroller is bell-shaped with blackish gray snoutlike mouthparts that protrude forward from the head. Forewings are dark rusty brown with a tan tip. Size varies from 0.38 to 0.5 inch (9.7–12.7 mm) long. Omnivorous leafroller larvae overwinter in weeds. In spring, larvae complete their development and moths emerge and lay shinglelike egg masses on leaves, which hatch after about 5 days. The larva does not roll leaves as its name suggests. Instead, it weaves a silk nest between two leaves, a leaf and a fruit, or where two fruit touch.

Damage

On pomegranates, the larvae typically carve surface grooves where two fruit touch or where the larvae have tied a leaf to the fruit surface. Often the larvae tunnel into the fruit. If skin penetration occurs, pathogens may become established internally and grow on the arils with no visible, external symptoms. If the fruit is not culled before juicing, the product may be ruined.

Management

Insecticide sprays timed according to degree-day accumulations may be used. Mating disruption can be effective if started in February or early March when moths first fly. A second hanging of dispensers may be needed in late summer. Careful monitoring, including occasional fruit and foliage inspections, is critical to the success of these management tools.

Biological Control

More than 10 species of parasites have been recorded from omnivorous leafroller. However, seldom does mortality from these parasites exceed 10%. Predators such as lacewings, minute pirate bugs and spiders also feed on omnivorous leafroller larvae.

Cultural Control

During the first flight, adults oviposit on weed hosts near the orchards, so weed control early in the season reduces the second generation that may cause damage to pomegranate orchards. Manage orchard weeds during late winter. Disc clusters and weeds to bury overwintering larvae living on weeds in ground duff. During dormancy, prune out old fruit and destroy by flailing or shredding.

Organically Acceptable Methods

Applications of Bacillus thuringiensis, spinosad (Entrust), and the use of mating disruption are organically acceptable.

Monitoring and Treatment Decisions

Monitor omnivorous leafroller adults with a minimum of 2 traps per block first placed in orchards at 5 to 6 feet high in the canopy around February 15 to 20. For blocks over 20 acres use an additional 1 trap per 20 acres. Check the traps at least one to two times per week until the first consistent moth catch (the biofix date). A treatment threshold based on trap moth catches has not been established. However, traps can be used to time a pesticide application.

Mating Disruption

If mating disruption is to be used, place pheromone dispensers out in February to early March or at the biofix. To ensure coverage through the long growing season, a second hanging of dispensers may be needed in the late summer (July). In some orchards, putting dispensers out once in mid-May, before the second generation moth flight begins, can provide control.

Pheromone dispensers will disrupt pheromone trap catches. Several times throughout the season, inspect foliage and fruit for leafrollers and damage to confirm that mating disruption is working. Several moths in traps can be an indication that pheromone disruption is not working.

Insecticides

Timing insecticides using degree-days in pomegranate has not been studied, but should resemble the timings that are used in stone fruits. Apply an insecticide about 700 to 900 degree-days (lower development threshold 48°F, upper threshold 87°F) after the first flight. If applying Bacillus thuringiensis, timing must be precise since Bacillus thuringiensis must be ingested to work and is most effective against small larvae. Bacillus thuringiensis has a short residual, should be applied twice about 7 to 10 days apart, is slow acting, and may not reduce numbers quickly.

Continue monitoring trap catches weekly until the second generation flight, about 1200 degree-days after the first flight in late June, treating 700 to 900 degree-days after the first flight.

The third generation, in late July or early August, is most damaging to fruit. If earlier control measures were adequate, additional third generation measures should not be necessary, but if pheromone traps or fruit inspections indicate a continuing problem, additional sprays can be aimed at the third moth flight 700 to 900 degree-days after the flight begins.

Common name Amount per acre R.E.I.‡ P.H.I.‡
(example trade name)   (hours) (days)

  Calculate impact of pesticide on air quality
 
The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used.
 
A. CHLORANTRANILIPROLE
  (Altacor) 3–4.5 oz 4 1
  MODE-OF-ACTION GROUP NUMBER1: 28
 
B. SPINETORAM
  (Delegate WG) 4–7 oz 4 1
  MODE-OF-ACTION GROUP NUMBER1: 5
  COMMENTS: Highly toxic to bees. Do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
C. METHOXYFENOZIDE
  (Intrepid 2F) 8–16 fl oz 4 7
  MODE-OF-ACTION GROUP NUMBER1: 18
 
D. METHOMYL*
  (Lannate SP) 1 lb 48 14
  MODE-OF-ACTION GROUP NUMBER1: 1A
  COMMENTS: Disruptive to natural enemies of mealybugs, caterpillars, soft scales, aphids, and other pests. Use of this material may result in outbreaks of these pests.
 
E. SPINOSAD
  (Entrust#) 1.25–2.5 oz
(0.45–0.83 oz/100 gal)
4 7
  MODE-OF-ACTION GROUP NUMBER1: 5
  COMMENTS: Highly toxic to bees. Do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
F. BACILLUS THURINGIENSIS ssp. KURSTAKI#
  (various products) Label rates 4 0
  MODE-OF-ACTION GROUP NUMBER1: 11.B2
  COMMENTS: Least harmful to natural enemies. Bacillus thuringiensis is a stomach poison and must be consumed by the leafroller. Must be applied when larvae are small. A second or third treatment may be required. Most effective if applied when weather forecasts predict 3 to 4 days of warm, dry weather. Larvae are more active and feed more in warm weather than in cooler or rainy weather.
 
G. MATING DISRUPTANTS#
  (Checkmate OLR) 100–150 units
 
Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) is the number of days from treatment to harvest. In some cases the R.E.I. exceeds the P.H.I.. The longer of two intervals is the minimum time that must elapse before harvest.
# Acceptable for use on organically grown produce.
1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode-of-action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.
Not applicable.
* Permit required from county agricultural commissioner for purchase or use.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Pomegranate
UC ANR Publication 3474

Insects and mites

  • E. E. Grafton-Cardwell, Entomology, UC Riverside and Kearney Agricultural Center, Parlier
  • D. Carroll, Bio Ag Services, Inc., Fresno
  • W. J. Bentley, UC IPM Program (emeritus), Kearney Agricultural Center, Parlier
  • D. R. Haviland, UC Cooperative Extension, Kern County
  • V. Walton, Horticulture, Oregon State University (filbertworm)

Top of page


Statewide IPM Program, Agriculture and Natural Resources, University of California
All contents copyright © 2014 The Regents of the University of California. All rights reserved.

For noncommercial purposes only, any Web site may link directly to this page. FOR ALL OTHER USES or more information, read Legal Notices. Unfortunately, we cannot provide individual solutions to specific pest problems. See our Home page, or in the U.S., contact your local Cooperative Extension office for assistance.

Agriculture and Natural Resources, University of California

Accessibility   /PMG/r621301111.html revised: April 25, 2014. Contact webmaster.